As someone who has been married 14 years, I'd like to operate under the assumption that you and your boyfriend will have a long happy relationship together!
So, here's a possible suggestion: Flip the whole thing on its head. Tell him that you want him to bring all of his dirty fantasies to you, his partner.
It's already a great thing that you are talking openly about porn! That's relationship honesty! So, maybe, the next time you are in the bedroom, encourage him to be honest and open up to you. Fight through the "ick" aspect and consider this: If you tell him that you think his deepest, nastiest sexual desires are hoteven if you just mean that it's hot that he's being honest with youwell, now you're offering him something that porn just can't give him: Erotica focused around the woman whom he truly cares about.
And THEN, it becomes incredibly easy for you to say, "And now, instead of logging on to your computer when you're away from me, I want you to close your eyes and imagine ME in that fantasy." As a man, I am telling you: If he HEARS YOU say the words of his dirty fantasy back to him, he is very, very likely going to take you up on this offer.
Heck...I'm telling you: this works SO well that, if there's ever a moment during those 2-3 times a week when you see him when you're just not "in the mood", all you have to do is sultrily whisper in his ear, "I'm sorry, I'm tired, but I want you to go to the bathroom right now and think about your naughty schoolgirl fantasy, and imagine me in it, being so bad for you. I want that for you, right now." Boom. Problem solved.
This isn't removing porn, this is replacing porn...with you. This is you being a super partner and making the effort to go meet him on his male turf. And in exchange...well, what do you want? More romance? Him centering your needs in bed? Pick a thing you want, and then tell him. He's GOING to want to give it to you, because you took this step for him:)